<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style>
			body{
				height:10000px;
			}
			div{
				width:600px;
				background: yellow;
				height:40px;
				position:fixed;
			}
		</style>
	</head>
	<body>
		<div>我是固定的</div>
	</body>
</html>
